|
B channels can be used as independent channels to simultaneously provide a variety of services such as data, voice, or imaging. They also have the flexibility to be bonded, as needed, to provide higher bandwidth for special needs such as video conferencing. A significant difference between PRI and traditional T1 is that non PRI T1 requires a portion of each channel to be allocated for signaling functions. This results in a reduction in effectiveness, efficiency, potential and bandwidth for most functions of each channel. With PRI, all signaling functions are provided by the 24th channel. This leaves each of the other 23 channels with a full 64 kbps which can be fully dedicated to bearer functions. One D channel can provide signaling functions for several other PRI lines. It is not uncommon for two D channels (one as primary, one for backup) to provide the signaling functions for a span of as many as 20 PRI lines. This frees the 24th channel of the remaining PRI lines so that they can be used as additional bearer channels. PRI provides many advantages over traditional T1. These include: dynamic channel allocation, call by call service selection, more PBX users can be supported, caller ID, messaging, and video conferencing. Because of increased efficiency provided by PRI, companies which switch to PRI from traditional T1 often find that they not only receive a much greater variety of services but often do not need to pay for as many trunks as they needed prior to the change. A T3 is a 45 mbps (megabits per second) circuit. T3 is the equivalent of 28 T1s. When the DSOs of a single T1 or T3 are specifically configured and combined to provide different functions such as PRI, voice, internet data, video conferencing, audio conferencing or video broadcasting, this is referred to as channelization. A channelized T3 can perform all of the above functions, and more, without the added expense of needing to combine T1s for each function, or needing to acquire separate T3s or fractional T3s for each function. Because a DS0 is a very small component of a T3, channel assignments can be extremely granular and specialized. DS0s within a T3 can be combined in any number to allow extremely precise function assignments. Channelization makes T3 an extremely versatile and adaptable service. As an example, virtually any combination channels within a T3 can be configured for PRI. PRI is predominantly carried over T1 lines, or grouped T1s, but occasionally, in heavy usage situations, T3s are configured to carry PRI.
(Click here to return to top of page)
 |
|
|
The advantages and limitations of bonded T1